Resources reporter

Convenience retailer 7-Eleven is set to reverse partially a three-year-old, $300 million deal when it allows ExxonMobil to resume branding on petrol stations on the east coast.

Almost 300 Mobil outlets were sold to 7-Eleven in 2010, under a deal that was expected to precipitate ExxonMobil's exit from all downstream operations in Australia.

But the two companies surprised the market on Thursday when they announced Mobil, which had continued to supply fuel to 7-Eleven since the sale, would have its branding returned to shop fronts in 2014.

In a veiled reference to that climate of uncertainty in the local fuel sector, ExxonMobil Australia chairman Richard Owen said the 7-Eleven deal ''highlights ExxonMobil's commitment to downstream operations''.

The companies gave little explanation for the change of strategy, but some observers believe it may be an attempt to capitalise on the growing demand for premium fuels in Australia.

Rival fuel retailers such as Caltex have recently reported strong demand for premium fuels over the traditional unleaded products, and some speculated that the century-old Mobil brand might be more attractive to consumers seeking quality than 7-Eleven, which is better known for ''slurpies'' and late-night fast food.

''Premium fuels are definitely increasing and if you look at the other three - Caltex, BP and Shell - they all have a proprietary-branded fuel, whereas 7-Eleven at the moment has more of that homogeneous product,'' said Nic Moulis of the Australasian Convenience and Petroleum Marketers Association.

If correct, the strategy would be at odds with comments made in 2010 by then 7-Eleven chairman Russ Withers, who said the convenience store chain would inject its branding into the sector.

''We don't want them to be just a Mobil site with the 7-Eleven sign above the door. We want to give it that 7-Eleven feel,'' he said in May 2010.

7-Eleven's entry to the petrol station sector was part of a trend in which retailers such as Woolworths and Coles entered the fuel market. Woolworths and Coles now have a commanding market share in the sector.

Service Station Association manager Colin Long said the deal was a surprise given the trend seemed to be for big oil companies to distance themselves from the ''downstream'' side of the industry.